Negative electrode for nonaqueous electrolyte secondary batteries, nonaqueous electrolyte secondary battery, and method for producing negative electrode for nonaqueous electrolyte secondary batteries

Abstract

A first negative electrode mixture layer contains a first negative electrode active material and a first water-soluble polymer material; and a second negative electrode mixture layer contains a second negative electrode active material and a second water-soluble polymer material. The ratio of the amount (S1) of the first water-soluble polymer material present on the surface of the first negative electrode active material to the amount (V1) of the first water-soluble polymer material present in voids among particles of the first negative electrode active material, namely S1/V1 is larger than the ratio of the amount (S2) of the second water-soluble polymer material present on the surface of the second negative electrode active material to the amount (V2) of the second water-soluble polymer material present in voids among particles of the second negative electrode active material, namely S2/V2.

1 . A negative electrode for a non-aqueous electrolyte secondary battery, comprising:
 a negative electrode current collector;   a first negative electrode mixture layer disposed on a surface of the negative electrode current collector; and   a second negative electrode mixture layer disposed on a surface of the first negative electrode mixture layer, wherein   the first negative electrode mixture layer includes a first negative electrode active material and a first water-soluble polymer material,   the second negative electrode mixture layer includes a second negative electrode active material and a second water-soluble polymer material, and   a ratio (S 1 /V 1 ) of an amount (S 1 ) of the first water-soluble polymer material present in a surface of the first negative electrode active material to an amount (V 1 ) of the first water-soluble polymer material present in voids between particles of the first negative electrode active material is higher than a ratio (S 2 /V 2 ) of an amount (S 2 ) of the second water-soluble polymer material present in a surface of the second negative electrode active material to an amount (V 2 ) of the second water-soluble polymer material present in voids between particles of the second negative electrode active material.   
     
     
         2 . The negative electrode for a non-aqueous electrolyte secondary battery according to  claim 1 , wherein at least one of the group consisting of the first negative electrode active material and the second negative electrode active material includes a Si material, and a content of the Si material is 0.5 mass % to 10 mass % based on a mass of the first negative electrode active material or the second negative electrode active material including the Si material. 
     
     
         3 . A non-aqueous electrolyte secondary battery comprising:
 the negative electrode for a non-aqueous electrolyte secondary battery according to  claim 1 ;   a positive electrode; and   a non-aqueous electrolyte.   
     
     
         4 . A method for producing a negative electrode for a non-aqueous electrolyte secondary battery, including:
 a first negative electrode mixture layer formation step of coating a surface of a negative electrode current collector with a first negative electrode mixture slurry prepared by kneading a first negative electrode active material and a first water-soluble polymer material, to form a first negative electrode mixture layer; and   a second negative electrode mixture layer formation step of coating a surface of the first negative electrode mixture layer with a second negative electrode mixture slurry prepared by kneading a second negative electrode active material and a second water-soluble polymer material, to form a second negative electrode mixture layer; wherein   a shear force in kneading of the first negative electrode mixture is larger than a shear force in kneading of the second negative electrode mixture slurry.